The present invention is directed to a cutting insert. More particularly, the present invention is directed to a titanium carbonitride-based cermet cutting insert (hereinafter referred to as TiCN), which exhibits superior wear resistance and toughness. Such a cutting insert is also longer lasting and resistant to damage such as chipping and breaking of the cutting edge while in continuous and discontinuous use.
In recent years, a demand for factory automation has created a need for longer lasting cutting inserts which are tough and wear resistant.
In an attempt to fulfill this demand for superior cutting inserts, Japanese Laid Open Patent Publication No. 62-170452 and 63-83241 discloses a TiCN-based cermet cutting insert which essentially contains from about 5 to about 30 vol % of a binding phase. The binding phase is mainly composed of Co and/or Ni, with the balance consisting of a hard dispersion phase.
The hard dispersion phase includes a duplex and/or a triplex phase structure with a core formed of a composite carbonitride solid solution (hereinafter referred to as (Ti,M)CN) composed of Ti and one or more elements selected from the group consisting of W, Mo, Cr, Ta, Nb, V, Hf, and Zr. This prior art cutting insert further contains a hard dispersion phase which includes a single phase structure composed of (Ti,M)CN.
Prior art TiCN-based cermet cutting inserts are plagued by numerous drawbacks. Chief among them is their inability to continuously cut steel in an industrial setting. Notwithstanding the toughness of prior art cutting inserts, such inserts are prone to extensive breakage and chipping of their cutting edges while continuously cutting steel. This drawback, in turn, impairs their usefulness and substantially shortens their lifespan.
The shortened life span, in turn, increases the overall cost of using prior art cutting inserts in both the cost of replacement of cutting inserts and the cost of machine downtime and labor to permit the replacement to be done.